MFC r257641:
 When building the textproc/docproj port, the ports-mgmt/pkg port
 needs /var/run/ld-elf*.so.hints, which is not automatically created.

 Fix reldoc build by running the ldconfig(8) startup script in the
 chroot directory before starting the port build phase.

Approved by:	re (kib)
Sponsored by:	The FreeBSD Foundation